Until now, monitoring has been carried out in each individual wind energy installation to determine whether this installation is operating correctly, that is to say whether all the state data is in the specified range. If a discrepancy from correct operation is found, then a defect message is produced, and is sent to a monitoring centre. The defect messages are analysed in the monitoring centre, and the repair measures to be carried out on the relevant wind energy installation are defined. The defect messages are processed in the time sequence of their arrival.
Particularly in the case of large offshore windfarms, this processing of defect messages leads to undesirable effects. As is known, wind energy installations must be subjected to regular servicing after a predetermined operating time. In the case of offshore windfarms, the regular servicing is associated with considerable effort, because the servicing personnel and the tools required must be taken to the wind energy installations by boat. It is therefore financially worthwhile to carry out the servicing on as many wind energy installations as possible at the same time. Even if, as is normal practice in the case of offshore windfarms, all the wind energy installations were commissioned at the same time, the servicing is not necessarily due at the same time. This is because the time for servicing is not primarily governed by a specific time period having passed but by a specific amount of electrical energy having been produced. In particular because of failure times of different duration or wind conditions, the electrical energy produced by a specific time may vary to a major extent from one wind energy installation to another. This can lead to the regular servicing being due for one wind energy installation at a time when only 95% of the electrical energy for this servicing interval has been produced in another wind energy installation. If servicing is nevertheless also carried out at this time for this wind energy installation, a portion of the servicing interval is lost. If, in contrast, the servicing of this wind energy installation is carried out later, then it is no longer possible to expect that simultaneous servicing will be possible for the subsequent servicing interval. Against this background, it is desirable for the servicing of all the wind energy installations in the windfarm to coincide as far as possible in time.